I'm considering using the Arduino for controlling the charging of a battery from a solar panel, but I'm more or less clueless on how to do this. Anyway, I was thinking the following:
The 12V battery should receive charging from the solar panel until the voltage of the battery reach xxV (13V maybe?). When this happened the Arduino breaks the connection between the battery and the solar panel. Once the output from the battery drops to below nnV (11V maybe?) the solar panel and battery are connected again.
Anyone that can judge if the above is an acceptable and practical way of doing this?
And btw: The reason why I want to use the Arduino for this, and not just a cheap charger control box, is that I in addition want to send the charging status and battery voltage level through a wireless connection, to a host computer.
The arduino can measure the battery voltage, but you need to drop it down to a value less than 5 volts. If your battery will never be above 15 volts, you can use a voltage divider that divides the voltage by 3.
There is an online calculator here, the values you want are 10k and 5k ohms for R1 and R2
Monitoring battery voltage with the arduino was discussed in a recent thread, you may want to do a search.
You will still need a charging circuit appropriate for the type of battery you are using. You can probably find many examples with a search on google
This should be possible. What you are looking to replace is a solar charge controller with remote monitoring.
There is a lot of info on the web about charge voltages for different types of batteries. Don't get overwhelmed by the high end technical aspects of "perfect charging". Start simple and work up from there. Figure out the type of battery you are going to charge and that should give you a voltage at which to disconnect the solar panel. Reconnect it as a voltage lower than that, but not so low as 11 volts.
Once you get that working, add features one at a time. Eventually you will have a 3 state temperature compensated solar charger.
And btw: The reason why I want to use the Arduino for this, and not just a cheap charger control box, is that I in addition want to send the charging status and battery voltage level through a wireless connection, to a host computer.
As I don't know anything about charging batteries (except that my motorcycle is not very good at it!) my suggestion is a bit of a hack.
Most/all chargers has a few LEDs to indicate charging status. Connect the positive pin of the LED to a digital pin on the Arduino (assuming 5v to the LED - check this first!) and read the pin(s) to detect charging status. Monitor the battery voltage using an analog pin and a voltage divider as suggested.
You can also make a very simply, easy-to-make trickle charger that will properly keep the battery conditioned for a few bucks in parts using an LM317 - see application #8 in the LM317 datasheet: http://www.sparkfun.com/datasheets/Components/LM317.pdf
Then you also don't have to worry about cutting the charge off, running a switch, etc. The circuit acts as one - you could measure the voltage coming out of it to determine where its at in the charging cycle.
Drone> That might not be a bad idea. However, I looked at the datasheet for the LM317 and I don't really understand how the cercuit in figure 8 can trickle charge the battery. How does this cercuit knows what the input to the battery should be? Do I have to adjust the value of the resistor, based on the battery I'm using?
Rs determines the current, you would switch this to higher value to trickle charge when the battery voltage reached the appropriate level. Figure 8 does not show the additional circuit needed to monitor the battery voltage and switch the resistor. You may find some worked examples for your kind of battery with a google search
Hi,
did you get anywhere making a program? I'm looking to make something basic for a wind turbine but don't know any code for the arduino, I'm looking for a starting point.
Bests,
Dan